These adult least auklets and eggs arranged on Alaska's Kiska Island by scientists were preyed on by non-native rats during a recent field study.

Around the world rodents are attacking seabird nesting colonies—consuming eggs, chicks, and even adult birds, says a global analysis released in February 2008.

"Island ecosystems are especially vulnerable to induced change, and more extinctions have taken place on islands than anywhere else," said Alan Saunders, director of the Cooperative Islands Initiative at the University of Auckland, in New Zealand.

"On many islands around the world rats are the critical extinction factor."